South Pole Diaries 1997/98

   

   


Tuesday 18th November - Nism up

From John Storey

The last 24 hours have been particularly eventful. (These missives are written directly after dinner, when it's impossible to move for an hour or so until dinner settles.)

Yesterday evening began with a bang when we fired up the MISM. (Regular readers will recall that the power supply card in the NISM had previously been deemed unsuitable for up-firing, on account of the self-incineration of the high-side switch). Anyway, we plugged in the MISM and were immediately greeted by the cheery little red led on the front panel, and the nice bright green one on the power supply card itself.

It took a few seconds before I remembered we don't *have* a green led on the power supply card, a recollection that was reinfiorced by the clouds of acrid smoke cominng from the vicicnity of the high-side switch. Things were not looking good for a) getting anything to work at all b) high-side switches in general c) Siemens nuclear-bomb-proof high-side switches in particular c) the reputation of quality German engineering (the only other German things in the AASTO are the Sonnenscheins).

When the smoke cleared it became apparent that all that had happened was that the brown slime had bridged across from the case of the high-side switch to ground, and was enjoying its last moments of glory. A quick squirt with general purpose detergent (unsuitable for food-preparation surfaces), and a bit of a scrub and everything was right as rain.

The mism power supply voltages all came up fine, so we tried to telnet to it but got no response. Then we plugged the mism power supply board into the nism and fired that up - it looked happy but we couldn't telnet to it either.

We measured lots of voltages, peered at the PC104 stack and reminded each other of how awful it was taking it apart, typed in random commands to poodle, wiggled connectors, briefly tried to visualise how beautiful life could be if computers had never been invented, and packed it in for the night.

This year we're lodged in the "Elevated Dorm", the blue building with the satellite dish on top. It is actually very comfortable - much more room than the Jamesways, *quiet*, and with the shower and the Head all in the same building. It's a comfortable temperature (sort of), and even has cupboards and drawers. The only downside is having to share a room with Ant...

Also they got the phone in the AASTO fixed, so now it's a bit safer working in there. We still haven't got our fire extinguisher back, despite asking for it at least twice a day since we arrived. If it does catch fire we can try throwing snow on it, but 4,000lbs of liquid propane will probably require quite a bit of snow.

Ev Paschal was out at the AASTO bright and early this morning, and got straight to work trying to figure out what had gone wrong with the TEG. Ev is great. Not only is he a good bloke, but he had no hesitation in immediately getting out the sponge and the general purpose detergent and scrubbing down all the grunge that we'd deliberately not cleaned from TEG so Ev could look at it. A PhD engineer who doesn't mind getting his hands dirty is a valuable asset in Antarctica.

Unfortunately it quickly became clear that the AASTO is totally and utterly stuffed. The stainless-steel exhaust pipe is corroded through completely where it goes through the ceiling, and is completely blocked with green and yellow indescribable lumps of crud. Ev took photos of it. We could tell things were bad because Ev kept saying things like "Oh boy". It seems unlikely the TEG can be fixed this season, but we'll see what ASA can do. It's amazing that something as inert as freon can be converted into an unstoppable stainless-steel-munching fibreglass-dissolving brown-goo-creating circuit-board-illuminating monster chemical simply by passing it over platinum beads at a few hundred degrees. Any of the 50lbs of freon that didn't decompose has by now wandered off to the stratosphere to munch holes in the ozone layer.

At about the time we had the AASTO covered in yet another pile of yellow and white grunge, and were picking up pieces of what used to be stainless steel and/or fibreglass, in walks the station manager, station science manager, and health and safety officer. They stood around for a bit shaking their heads and saying things like "smells bad" and "might be mercaptan" and "oh boy", and than left before anything bad happened to their health. I reminded them about the fire extinguisher as they left.

We then pulled the TEG apart, and it's kind of ugly and corroded inside. Worse, it's full of rockwool insulation, which is now over everything. Ev says it's not carcinogenic. I believe it's made out of basalt, but have no idea how. It may involve soaking rocks in the brown slime they get out of AASTOs.

Now for the good news. While we were sleeping Michael Ashley crept out of his bed, telnetted to the "super", and fixed up the software!! Apparently we'd been using the wrong version.

With that fixed, instant success! We lit up the nism and immediately poodle was able to engage it in animated converstation. The only problem was that all the nism would send back was rows of little square boxes. To a geek that means only one thing - baud rate. Being geeks we changed the baud rate of the super to 19,200 (a figure we chose at random), and sure enough it sprung into life.

A quick check out shows: adc bb = -17.8C adc volts = 25.51 adc amps = 202.6 mA The rotator works, and calibrates. The cooler works - 96K after a few minutes. Choptest doesn't work. First, if you ask for 20 seconds it only takes data for two. Secondly, it gives the numbers you want, even if they're wrong. I think it's being overly polite. For example, if I set the chop frequency to something impossible, "choptest" runs and tells me everything is just fine.

To attack this problem further we grabbed a Tektronics digital cro from MAPO (the Phillips having mysteriously re-appeared, minus knob, back at UNSW), and probed the chopper driver card. I *hate* oscilloscopes that are more intelligent than I am. This one is so smart that took me a good half hour just to figure out that in fact the chopper is working perfectly, and generating all the right reference signals. The phase- locked loop works between about 50Hz and 82Hz.

Now that dinner has settled (home-made bread, spatchcocks, cous-cous, fresh lettuce, carrot, plus freshly-ground coffee and lemon-raisin pie), we'll go out and actually see if the detector works. If so, we'll have scored one out three working instruments already.

Cheers, John

 

 

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